Hand-Held Power Tool

ABSTRACT

The invention relates to a hand-held power tool having a bearing ring ( 19 ) inserted into a bearing receptacle ( 18 ), wherein the bearing receptacle ( 18 ) and the bearing ring ( 19 ) have recessed ring sectors ( 17 ) positioned relative to one another in an overlapping manner, of which the ring sector ( 17 ) of the bearing ring is configured by breaking out a circumferential section ( 22 ) of the bearing ring ( 19 ), which is defined by predetermined breaking points ( 20 ).

This application is a divisional of co-pending application Ser. No.12/745,422, filed on May 28, 2010 (now U.S. Pat. No. 8,561,714), whichin turn is a 35 U.S.C. §371 National Stage Application ofPCT/EP2008/063024, filed Sep. 29, 2008, which claims the benefit ofpriority to Serial No. 10 2007 057 453.5, filed Nov. 29, 2007 inGermany, the disclosures of the US application, the PCT application, andthe DE application being incorporated herein by reference in theirentirety.

The invention relates to a hand-held power tool as recited in thepreamble to claim 1 as well as an assembly process for it.

PRIOR ART

Hand-held power tools of the type mentioned above, with an outputelement that is guided in a bearing race, which is situated in anannular, encompassing bearing socket, are known from practicalexperience. The part of the bearing socket surrounding the bearing raceis constituted by the free end of a neck of an intermediate flangethrough which the output element extends. A radial access to the outputelement, whether for drive purposes and/or in connection with theassembly process, is only possible outside the region of the bearingsocket due to the closed embodiment of the bearing race and bearingsocket. This has a negative impact on assembly options and on thepossibilities for access to the output element on the drive side andrequires a corresponding overall length for the intermediate flange inthe positioning of the drive access in the region of the intermediateflange.

The as yet unpublished German patent application DE 10 2007 014 758 hasalready proposed having the bearing socket and bearing race for anoutput element in a hand-held power tool be embodied in the form of anopen ring when cut-out ring segments are situated congruent to eachother.

DISCLOSURE OF THE INVENTION

Based on a hand-held power tool of the type mentioned at the beginning,the object of the invention is to expand the possibilities for accessingthe output element without thereby complicating the installation of thebearing race in the bearing socket and/or negatively impacting theguidance quality of the bearing race for the output element.

This object is attained according to the invention with a hand-heldpower tool as recited in claim 1 and by means of an assembly method forsuch a hand-held power tool as recited in claim 4.

In the hand-held power tool according to the invention, the bearingsocket and the bearing race are embodied in the form of an open ring,with cut-out ring sectors that are situated congruent to each other andthe cut-out ring sector of the bearing race is embodied so that acircumference segment—which is delimited by detachment points, inparticular desired fracture points—is detached, in particular brokenout.

This embodiment of the bearing race makes it possible not only tomanufacture it as a closed bearing race, but also to insert it in aprecisely fitting way into the surrounding circular or oval annularbearing socket so that regardless of manufacture-dictated and/ormaterial-dictated inherent stresses, the bearing race is in its desiredshape for the insertion into the bearing socket and due to the supportof the bearing socket, maintains the manufactured shape that is designedfor being supported in a dimensionally stable fashion in the bearingsocket even when the open ring form is produced by removing, inparticular breaking out, the circumference section delimited bydetachment points, in particular desired fracture points.

As a result, the same installation prerequisites exist as for a closedbearing race and, in accordance with matching dimensional ratios, thebearing race can be inserted without hindrance into the bearing socketin accordance with the respective fit conditions present. Anymaterial-dictated and/or manufacture-dictated inherent stresses in thebearing race that could result in deviations from the predetermineddesired shape in the case of the open ring form thus continue to have noeffect on the installation and lastly, have no negative effect on theguidance quality of the bearing race for the output element even afterthe breaking-out of the circumference section delimited by the desiredfracture points, since for the bearing race that is now open, thebearing socket constitutes a dimensionally stable support that is alsosufficient for the optional form-locked anchoring of the bearing race inthe bearing socket. For such an anchoring, in particular arotationally-fixed mounting, of the bearing race, it is also optionallypossible for grooves to be additionally provided, preferably on the endsurface, which cooperate with corresponding counterpart elementsprovided in the bearing socket to assure the required fixing andpossibly also axial positioning of the bearing race.

The assembly method according to the invention is particularly suitablefor bearing races that are preferably embodied in the form of slidebearing races composed of brittle materials, primarilybrittle-fracturing materials. These materials particularly includesintered materials or other materials prone to brittle fracturing inwhich inherent stresses also arise during manufacture, which can resultin deviations from the desired shape when the bearing race is in thebroken-open state.

Furthermore, the invention also relates to a bearing race as such thathas a ring section—which is delimited by detachment points, inparticular desired fracture points, and is to be detached, in particularbroken out—that can in particular be used in hand-held power tools ofthe above-mentioned type as well as in connection with anabove-mentioned assembly method and which, despite its provided use asan open bearing race, is to be produced in a closed form and thus canalso be composed of materials in which, as in sintered materials,inherent stresses can arise during their manufacture and could result indeformations in the discontinuous, i.e. open, bearing race.

In the scope of the invention, the desired fracture points can beembodied in the form of notches provided in the inner and/or outercircumference of the bearing race, possibly notches that are situatedcongruent to each other, so that only comparatively thin bridge piecesremain.

In connection with notches provided on one side, in particular on theinside, it can be useful to provide a thickened region on the outercircumference of the bearing race in the region coinciding with eachnotch in order, during the manufacture, to achieve a continuous,essentially uniform material cross section regardless of the presence ofthe notch. The thickened region can be easily removed after themanufacture, for example after the pressing procedure when usingsintered materials, by means of grinding, stripping, or similarmachining procedures.

With regard to the rotary securing of the bearing race, it can be usefulto also provide it with notches in the end surface, which are associatedwith corresponding counterpart elements on the respective bearingsocket.

Other advantages and suitable embodiments can be inferred from theclaims, from the description of the figures, and from the drawings.

DRAWINGS

FIG. 1 is a simplified depiction of a rotary hammer as an example of ahand-held power tool embodied according to the invention,

FIG. 2 is a perspective depiction of an intermediate flange of therotary hammer, which, terminating its end oriented toward the tool, hasa bearing with a bearing socket for a bearing race, which guides theoutput element to be connected to the tool,

FIGS. 3 and 4 show the bearing race in a perspective view and a viewfrom the end surface,

FIG. 5 is an enlarged depiction of the detail V from FIG. 4,

FIG. 6 is an enlarged partial top view of a bearing race in which aregion of the bearing race that is notched on the inside is thickened onthe outside, and

FIG. 7 is another perspective depiction of a bearing race.

The hand-held power tool is schematically depicted in FIG. 1 in the formof a rotary hammer 1, which at its working end 3 remote from the handle2 has a tool holder associated with an output element 4. The outputelement 4 is embodied in the form of a hammer tube 5, which, to the rearof the tool holder, accommodates a hammer piston 6 that is driven in anoscillating fashion, in particular oscillating in a reciprocatingfashion, and is supported at its end remote from the tool holder bymeans of a bearing position 7 on the neck 8 of an intermediate flange 9.The intermediate flange 9 has a base plate 10 that is connected to theoutput side end plate 11 of the electric motor 12 provided as the driveunit, whose output shaft 13 drives an intermediate shaft 14. By means ofa wobble bearing 15, the intermediate shaft 14 drives a wobble pin 16that reaches through the neck 8 of the intermediate flange 9 to engagethe hammer piston 6. In accordance with the wobbling motion, i.e. thereciprocating pivoting motion of the wobble pin 16, the annular neck 8through which the wobble pin 16 reaches, according to FIG. 2, has acut-out extending for at least a significant portion of its length andacross a ring sector 17; this cut-out also extends across the region ofthe bearing position 7, which is provided at the end of the neck 8opposite from the base plate 10 of the intermediate flange 9. Thisbearing position 7 is constituted by a bearing socket 18 that is offsettoward the outside in stepped fashion, into which a bearing race 19 isinserted; in the depiction according to FIG. 2, the cut-out ring sector17 is depicted as extending continuously and for essentially the samespan across the neck 8 and the bearing position 7.

With regard to the intermediate flange 9, the cut-out of thecircumference section corresponding to the ring sector 17 can beembodied in the usual way during manufacture, for example by means ofthe die-casting method. However, it is also possible for a circumferencesection—which corresponds to the ring sector 17 to be cut out—to beremoved, in particular machined out or broken out, from the neck 8 ofthe intermediate flange 9, which is initially closed.

The bearing race 19 is inserted axially into the bearing socket 18 thatis opened by means of the cut-out ring sector 17, in fact in the form ofa closed bearing race whose circumference section 22 situated congruentto the cut-out circumference section of the bearing socket 18 isdelimited by detachment points, in particular desired fracture points20, as shown in a closed bearing race in FIGS. 3 through 7. In thedepiction according to FIG. 3, the ring sector 17 of the bearing race 19to be cut out is comprised of a circumference section 22 that isdelimited by wedge-shaped notches 21 and is to be broken out.

The bearing race 19, which like the bearing socket can have a circularor oval shape, is first inserted into the bearing socket 18 in the formof a closed ring and with the circumference section 22 to be broken outpositioned congruent to the cut-out ring sector 17 of the bearing race18, preferably in a precisely fitting way, so that a dimensionallystable support for the bearing race 19 is provided, which is onlymissing in the region of the ring sector 17 to be cut out, and thecircumference section 22 of the bearing race 19 can be broken out alongthe desired fracture points 20 and detached from the ring piece withoutimpairing the dimensional stability of the bearing race 19.

FIGS. 3 through 5 show the embodiment of the desired fracture points 20provided as detachment points and embodied in the form of acute-anglednotches 21, as shown with particular clarity in the enlarged depictionin FIG. 5, and the closed bearing race 19 whose circumferential shapecorresponds to that of the bearing socket 19 has only a relatively smallwall thickness remaining at the bottom of the notch. The notch angle inthe depiction in FIG. 4 is preferably approximately 60 to 80°.

If such an embodiment of desired fracture points 20 by means ofwedge-shaped notches 21 that significantly reduce the wall thickness ofthe bearing race 19 or in the form of channel-shaped, rounded, orgroove-shaped rectangular recesses leads to difficulties in producingthe bearing race 19, which can be the case particularly if the bearingrace 19 is produced by casting or sintering, then according to theinvention, the circumference region on the other side from the recess ofeach notch 21, which is in particular wedge-shaped, can be provided witha thickened region 23 as shown in FIG. 6 so that in the region of thenotches 21 as well, the thickened region 23 initially provides a wallcross section that corresponds to the wall thickness of the rest of thebearing race 19. The thickened region 23 whose removal is required forinsertion into the bearing socket 18 can then be abraded away, forexample by means of grinding, stripping, or the like so that with thisproduction-dictated embodiment of the still-closed bearing race 19, oncethe thickened region 23 is abraded away, the bearing race 19 can beinserted into the bearing socket 18 in the above-described way.

Basically, it is also possible to abrade away the thickened region 23only in the region coinciding with the circumference region to be brokenout and thus to embody projections in the transition from the cut-outcircumference region 22 on the bearing race 19, which projections, byengaging radially over or in the bearing socket 18, assure a rotationalfixing of the bearing race 19.

Such a rotational fixing can also be achieved in a different way, forexample according to FIG. 7, by means of recesses 24 on the end surfaceof the bearing race 19, for which corresponding counterpart elements,not shown, are provided on the bearing socket.

1. A hand-held power tool, in particular a chisel hammer and/or rotaryhammer, having an output element (4) that accommodates a tool and isguided in a bearing race (19), which is situated in an encompassingbearing socket (18), characterized in that the bearing socket (18) andthe bearing race (19) are embodied in the form of an open rings havingcut-out ring sectors (17) situated congruent to each other and thecut-out ring sector (17) of the bearing race (19) is comprised of acircumference section (22) that is delimited by detachment points(desired fracture points 20) and is broken out.
 2. The hand-held powertool as recited in claim 1, characterized in that the open bearing race(19) is accommodated in a dimensionally stable fashion by the circularor oval bearing socket (18).
 3. The hand-held power tool as recited inclaim 1, characterized in that the open bearing race (19) is held in thebearing socket (18) in a precisely fitting, in particular form-locked,fashion.
 4. An assembly method for a hand-held power tool, which has abearing race (19) situated in an annular bearing socket (18), inparticular as recited in one of the preceding claims, characterized inthat the bearing race (19) is inserted in the form of a closed ring intothe bearing socket (18), which is embodied in the shape of an open ringand has a cut-out ring sector (17), and a bearing race circumferencesection (22)—which is delimited by detachment points (desired fracturepoints 20) and is situated congruent to the cut-out ring sector (17) ofthe bearing socket (18)—is detached from the bearing race (19), inparticular broken out from it.
 5. A bearing race, particularly for ahand-held power tool as recited in claim 1, which is for insertion intoa bearing socket (18), characterized in that the bearing race (19) has acircumference section (22), which is delimited by detachment points(desired fraction points 20) and is to be detached.
 6. The bearing raceas recited in claim 5, characterized in that the bearing race (19) hasdesired fracture points (20) serving as detachment points for thecircumference section (22) and the circumference section (22) is to bebroken out.
 7. The bearing race as recited in claim 5, characterized inthat the desired fracture points (20) are embodied in the form ofnotches (21) provided in the inner and/or outer circumference of thebearing race (19).
 8. The bearing race as recited in claim 7,characterized in that the notches (21) provided in the inner and/orouter circumference of the bearing race (19) are situated opposite eachother, in particular symmetrically opposite each other.
 9. The bearingrace as recited in claim 7, characterized in that the bearing race (19)is thickened on the outside in the region that coincides with at leastone of its notches (21) provided on the inner circumference.
 10. Thebearing race as recited in claim 9, characterized in that the outline ofthe thickened region (23) follows the outline of the notch (21).
 11. Thebearing race as recited in claim 10, characterized in that the wallthickness of the bearing race (19) is approximately the same in theregion of the notch (21) due to the presence of the thickened region(23) situated to coincide with the notch (21).
 12. The bearing race asrecited in claim 5, characterized in that the notches (21) are embodiedin the form of angled grooves, in particular acutely angled grooves. 13.The bearing race as recited in claim 5, characterized in that thebearing race (19) is provided with recesses (24), in particular grooves,on its end surface to permit it to be situated in a bearing socket (18)in a rotationally fixed fashion.
 14. The bearing race as recited inclaim 5, characterized in that the bearing race (19) is composed ofbrittle-fracturing materials, in particular is composed of a sinteredmetal body.